Electrical enclosures have long been used in both power transmission and telecommunications transmission to house devices which terminate electrical wires or cables. These terminal devices referred to as "terminal blocks", are supported inside the enclosure. Openings are provided through the enclosure so that electrical cables may be passed therethrough for electrical termination to the terminal blocks. When enclosures such as these are used outdoors, they are exposed to the elements. Water and other contaminents such as dirt, small debris and insects, which may enter the enclosure through the cable entry openings, could adversely affect the connections of the cables to the terminal block.
The art has seen a variety of barrier type devices which permit passage of the cable through the opening, yet restrict the passage of water and other contaminents therethrough. U.S. Pat. No. 3,523,156 shows an improved moisture barrier for an electrical pedestal. The device includes a rubber sealing member having openings therethrough in line with the cable entry openings. The opening in the sealing member surrounds the electrical cable in sealing engagement, restricting the tendency of water to track along the cable and into the enclosure. However, in order to prevent water from entering the cable entry opening when a cable is not inserted therethrough, a separate plug must be inserted therein. The limitations of such a separate plug are readily apparent.
Other enclosures include rubber sealing members including a thin membrane which spans the cable entry opening, thus effectively closing the opening when no cable is inserted therethrough. To provide cable access through a particular opening, the cable is inserted through the membrane to puncture the membrane, thus providing access to the interior of the enclosure. However, with these membrane-type sealing devices, once the cable is removed, the membrane is violated and water passage therethrough is not restricted.
It is desirable to provide an enclosure for an electrical terminal block having cable entry openings, which provides a barrier at the cable entry opening. The moisture barrier should effectively restrict water and other small contaminents from passing therethrough prior to cable insertion, while the cable is inserted and after the cable has been removed.